It is known to produce fluorinated compounds, such as hydrofluorocarbons, by fluorination of chlorinated compounds, such as hydrochlorocarbons in particular. This fluorination is generally a catalytic fluorination using hydrofluoric acid (HF) as fluorinating agent.
During this type of reaction, hydrochloric acid (HCl) is coproduced. It is known to separate the HCl from the other gases produced via a distillation column and then to absorb the HCl in an adiabatic absorption column in order to generate an HCl solution of commercial type.
The document FR 1507252 describes stages of treatment on active charcoal, at high temperature and in the presence of water, and of washing with concentrated aqueous hydrochloric acid.
The document U.S. Pat. No. 3,353,911 describes the purification of an HF/HCl gas mixture by bringing into contact with an absorbent solution which is a saturated boric acid solution.
However, the known techniques for the purification of hydrochloric acid do not make it possible, in some cases, to achieve the required HCl purity.
There thus exists a need to provide an improved process for the purification of hydrochloric acid in a gas stream.